PSI - Issue 17

Z. Marciniak et al. / Procedia Structural Integrity 17 (2019) 503–508 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

508

6

Table 1. Mechanical properties of C45 steel.  Y (MPa)  U (MPa) E (GPa)

A 5 (%)



547 17.5 The obtained results allow determine the energy characteristic curve ( − ) of the material (Fig. 5). Regression coefficients were determined according to the ASTM Standard E 739-91. The correlation coefficient at the significance level  = 0.05 is equal to 0.94. log = + ∙ , (5) where: A = 7.53 and m = -6.75 are determined parameters of the regression equation. The bold blue line represents the line described by Eq. (5), and two slim lines represent 95% confidence interval. 4. Conclusions The paper presents the procedure for determining the strain energy curves for structural materials directly from experimental tests. This characteristic is essential in the fatigue life estimation algorithm especially for variable amplitude or random loading. Various hypothesis related to the cumulative fatigue damage can be employed once the parameters A and m of the curve are known. Lachowicz CT. Calculation of the elastic – plastic strain energy density under cyclic and random loading, Int. J. Fatigue 2001;23:643-652. Smith K., Watson P., Topper T. A stress-strain function for the fatigue of metals. J. Materials, 1970;5:767-779. Glinka G., Shen G., Plumtree A. A multiaxial fatigue strain energy density parameter related to the critical fracture plane. Fatigue and Fracture Engineering Materials and Structures, 1995;18:37-46. Gołoś K. An energy based multiaxial fatigue criterion. Engineering Transactions, 1988;36:55 -63. Macha E., Sonsino M. Energy criteria of multiaxial fatigue failure. Fatigue Fract. Engng. Mater, Struct., 1999;22:1053-1070. Rozumek D., Marciniak Z., Lachowicz C. T. The energy approach in the calculation of fatigue lives under non-proportional bending with torsion. Int. J. of Fatigue 2010;32(8):1343-1350. Rozumek D., Marciniak Z. Fatigue properties of notched specimens made of FeP04 steel. Materials Science 2012;47(4): 462-469 . Mrozinski S. Stabilization of cyclic properties in metals and its influence on fatigue life. Rozprawa nr 128, Uniwersytet Technologiczno Przyrodniczy, Bydgoszcz 2008 (in Polish) Mrozinski S., Golanski G. Influence of temperature on analytical description of cyclic properties of martensitic cast steel. Journal of Metallurgical Engineering 2012;1(1):30-34 Marcisz E., Marciniak Z., Rozumek D, Macha E. Fatigue characteristic of aluminium alloy 2024 under cyclic bending with the controlled energy parameter, Key Engineering Materials 2014;592-593:684-687. Marcisz E., Marciniak Z., Rozumek D, Macha E. Energy fatigue characteristic of C45 steel subjected to cyclic bending, Key Engineering Materials 2014;598:147-152. Macha E., Słowik J., Pawliczek R. Energy based characterization of fatigue behavior of cyclically unstable materials, Solid S tate Phenomena 2009;147-149:512-517. Rozumek D., Marciniak Z. Control system of the fatigue stand for material tests under combined bending with torsion loading and experimental results, Mechanical Systems and Signal Processing 2008;22(6):1289-1296. Kasprzyczak L., Macha E., Marciniak Z. Energy parameter Control system of strength machine for material test under cyclic bending and torsion, Solid State Phenomena Vol. 198 (2013) pp. 489-494 Kasprzyczak L., Macha E.: Energy Parameter Control System of Strength Machine for Material Tests under Polyharmonic Bending and Torsion, Journal of Vibration and Control, Online Version of Record Dec 11, 2013, doi: 10.1177/1077546313514764, pp.6 739 215 0.29 References